RFR(S): 8139046: Compiler Control: IVGPrintLevel directive should set PrintIdealGraph

[Liu, Xin]

Hi, 

Could you review this webrev? It fixes a minor problem when users only use IGVPrintLevel in Compiler Directives. 
Jbs: https://bugs.openjdk.java.net/browse/JDK-8139046
Webrev: http://cr.openjdk.java.net/~xliu/8139046/00/webrev/

I move "bool should_print(int level)" from idealGraphPrinter to Compile because the later has the information. 
In this way, Compile can allocate _printer on demand. If Compile::should_print(level) return true,  it guarantees that Compile::printer() is not NULL. 
If users pass in CompileCommand="option,Hello::add,intx,IGVPrintLevel,3",  printer() will only turn on for that compiler thread. 

Ran hotspot:tier1 using fastdebug build. Only gtest/GTestWrapper.java failed. 
That's another issue. Currently, Openjdk can't execute any gtest because of a linkage error. 
Error occurred during initialization of VM
Unable to load native library: /backup/jdk/build/linux-x86_64-server-fastdebug/images/jdk/lib/libjava.so: symbol JVM_GetPermittedSubclasses version SUNWprivate_1.1 not defined in file libjvm.so with link time reference

Thanks,
--lx